Field of the Invention
The present invention relates to a sanitary washing apparatus that discharges wash water toward a private part of a user.
Description of the Related Art
A sanitary washing apparatus described in Japanese Patent Laid-Open No. 2001-90151 supplies wash water to a water discharge hole in a state in which a pressure of the wash water pulsates. Accordingly, a flow rate and a flow velocity of the wash water similarly pulsate, and the wash water is discharged such that the flow rate and the flow velocity pulsate and vary between a state of a maximum flow rate and a maximum flow velocity and a state of a minimum flow rate and a minimum flow velocity. Respective discharged water portions have a water discharge form in a state in which a discharged water portion having a maximum flow rate and a maximum flow velocity coalesces with a preceding discharged water portion to form a mass of water, and the mass of water is linked by a discharged water portion discharged later. A washing feeling of the sanitary washing apparatus is identified by a feeling of massiveness and a feeling of stimulation. In order to form a larger mass of water in the sanitary washing apparatus described in Japanese Patent Laid-Open No. 2001-90151, a pulsation amplitude of the wash water pressure needs to be increased. However, if the pulsation amplitude of the wash water pressure is increased, the discharged water portion having a maximum flow rate and a maximum flow velocity breaks through the preceding discharged water portion, and the catch-up and coalescence phenomenon does not occur.
In a sanitary washing apparatus described in Japanese Patent Laid-Open No. 2012-127107, a larger mass of water is formed by mixing bubbles into discharged water in addition to the catch-up phenomenon obtained by the pulsation of the wash water pressure described above. When bubbles are mixed into the mass of water as described above, the feeling of massiveness is improved, while it is difficult to improve the feeling of stimulation since the mass of water is softened.
In the sanitary washing apparatus described in Japanese Patent Laid-Open No. 2012-127107, increasing the pulsation amplitude of the wash water pressure as described above is considered as a solution to improve the feeling of stimulation. However, as mentioned in the description of the sanitary washing apparatus in Japanese Patent Laid-Open No. 2001-90151, it has been considered that the discharged water portion having a maximum flow rate and a maximum flow velocity breaks through the preceding discharged water portion when the pulsation amplitude of the wash water pressure is increased, and the catch-up and coalescence phenomenon does not occur.
However, as a result of intensive study, the present inventors have obtained a novel finding that, when bubbles are mixed into the discharged water under a certain condition, surface energy of the water stream is increased, and thus, even when the pulsation amplitude of the wash water pressure is increased, the water stream does not burst when the catch-up phenomenon occurs. The surface energy of the water stream is proportional to a total area of a gas-liquid interface of the water stream (a sum of an external surface area of the water stream and an internal area of the water stream in contact with the bubbles). The present inventors consider that the water stream is less likely to be deformed when the surface energy is increased.
By the way, in a case in which air is mixed into the discharged water by an ejector effect in a high-pressure band in which the wash water pressure is increased, a large amount of bubbles having a relatively large size are introduced. The large amount of introduced bubbles coalesce with each other by a surface tension with an elapse of time and grow up into larger bubbles. Since the surface energy of the water stream is dependent on the internal area in contact with the bubbles contained therein as described above, the coalescence of the bubbles results in a decrease in the internal area, so that the surface energy is gradually decreased. Thus, there occurs a new problem that the water stream bursts before reaching a private part of a user.
Thus, the present inventors have moved forward with their study to provide a sanitary washing apparatus which can prevent a water stream from bursting before the water stream reaches a private part of a user even when air is mixed into discharged water to which pressure variation in a high-pressure band is given in order to achieve both of a high feeling of massiveness and a high feeling of stimulation.
In order to solve the new problem, the present inventors considered that suppressing an amount of bubbles contained in wash water by decreasing an amount of wash water temporarily stored in a bubble mixture section may be one of effective means. However, when the amount of wash water temporarily stored in the bubble mixture section is decreased, the small amount of stored water is pushed out by a force of a water stream breaking into the stored wash water. Thus, it becomes difficult for the wash water to accumulate.
The present invention has been made in view of the problems as described above, and an object thereof is to provide a sanitary washing apparatus which can prevent a water stream from bursting before the water stream reaches a private part of a user even when air is mixed into discharged water to which pressure variation in a high-pressure band is given in order to achieve both of a high feeling of massiveness and a high feeling of stimulation, the sanitary washing apparatus capable of decreasing an amount of water stored in a bubble mixture section, and retaining the stored water.